JP7029423B2 - Manufacturing method of mask blank, transfer mask and semiconductor device - Google Patents

Description

The present invention relates to a mask blank for a phase shift mask, a phase shift mask, and a method for manufacturing a semiconductor device using the phase shift mask.

Generally, in the manufacturing process of a semiconductor device, a fine pattern is formed by using a photolithography method. A number of substrates, usually called transfer masks, are used to form this fine pattern. This transfer mask is generally a translucent glass substrate on which a fine pattern made of a metal thin film or the like is provided. The photolithography method is also used in the manufacture of this transfer mask.

As a type of transfer mask, a halftone type phase shift mask is known in addition to a binary mask having a light-shielding film pattern made of a chrome-based material on a conventional translucent substrate.
This halftone type phase shift mask is provided with a phase shift film pattern on a translucent substrate. This phase shift film transmits light with an intensity that does not substantially contribute to exposure, and causes a predetermined phase difference between the light transmitted through the phase shift film and the light that has passed through the air for the same distance. It has a function, which causes a so-called phase shift effect.

As disclosed in Patent Document 1, when the pattern of the transfer mask is exposed and transferred to the resist film on one semiconductor wafer by using an exposure apparatus, the pattern of the transfer mask is different from that of the resist film. It is common to repeatedly perform exposure transfer to a position. Further, the repeated exposure transfer to the resist film is performed at no interval. The exposure apparatus is provided with an aperture so that the exposure light is applied only to the region (transfer region) in which the transfer pattern of the transfer mask is formed. However, there is a limit to the accuracy with which the exposure light is covered (shielded) by the aperture, and it is inevitable that the exposure light leaks to the outside of the transfer region of the transfer mask. Therefore, the outer peripheral region of the region where the transfer pattern is formed in the transfer mask is
When the exposure is transferred to the resist film on the semiconductor wafer using an exposure device, the optical density (OD: Op: Op
It is required to secure tical Dimension). Normally, it is desirable that the OD is 3 or more (transmittance of about 0.1% or less) in the outer peripheral region of the transfer mask, and at least about 2.8 (transmittance of about 0.16%) is required. Has been done.

However, the phase shift film of the halftone type phase shift mask has a function of transmitting the exposure light at a predetermined transmittance, and the phase shift film alone has the optics required for the outer peripheral region of the transfer mask. It is difficult to secure the concentration. Therefore, as disclosed in Patent Document 1, in the case of a halftone type phase shift mask, a light semitransmissive layer (light shielding band) is laminated on the light semitransparent layer in the outer peripheral region, whereby the light semitransmissive light is transmitted. The laminated structure of the layer and the light-shielding layer ensures that the optical density is equal to or higher than the above-mentioned predetermined value.

On the other hand, as disclosed in Patent Document 2, as a mask blank of the halftone type phase shift mask, a halftone phase shift film made of a metal silicide-based material and a light-shielding film made of a chrome-based material on a translucent substrate. A mask blank having a structure in which an etching mask film made of an inorganic material is laminated has been known for a long time. When a phase shift mask is manufactured using this mask blank, first, the etching mask film is patterned by dry etching with a fluorine-based gas using the resist pattern formed on the surface of the mask blank as a mask. Next, the light-shielding film is patterned by dry etching with a mixed gas of chlorine and oxygen using the etching mask film pattern as a mask, and the phase shift film is further patterned by dry etching with a fluorine-based gas using the light-shielding film pattern as a mask.

Japanese Unexamined Patent Publication No. 7-128840 International Publication No. 2004/090635

In recent years, in the exposure technology using an ArF excimer laser (wavelength 193 nm) as the exposure light,
As the transfer pattern becomes finer, it is required to correspond to the pattern line width smaller than the wavelength of the exposure light. In addition to ultra-high NA technology (immersion exposure, etc.) with NA = 1 or higher, SMO (SMO) is a light source and mask optimization technology that optimizes the illumination of the exposure equipment for all patterns on the mask.
Source Mask Optimization) is beginning to be applied. The lighting system of the exposure apparatus to which this SMO is applied is complicated, and when the exposure light is irradiated by setting the phase shift mask in the exposure apparatus, the exposure light is applied to the light-shielding film (light-shielding band) of the phase-shift mask. On the other hand, it may be in a state of being incident from multiple directions.

The conventional light-shielding film is based on the premise that the exposure light transmitted through the phase-shift film at a predetermined transmittance is incident from the surface of the light-shielding film on the phase-shift film side and emitted from the surface opposite to the phase-shift film. The light-shielding performance (optical density) is determined. However, when the exposure light of the above complicated lighting system is applied to the phase shift mask, the exposure light that has passed through the phase shift film and is incident from the surface of the light shielding film on the phase shift film side is the light shielding band. It was found that the emission from the side wall of the pattern is more likely to occur than before. Since the amount of exposure light (leakage light) emitted from such a pattern side wall is not sufficiently attenuated, the resist film provided on the semiconductor wafer or the like is exposed to light, albeit a little. If the region where the transfer pattern of the resist film is arranged is exposed to light even a little, the CD (Critical Dimension) of the resist pattern formed by developing the transfer pattern exposed to the region is greatly reduced.

FIG. 3 is an explanatory diagram when the transfer pattern of the phase shift mask is repeatedly transferred to the resist film on the semiconductor wafer four times. Image I ₁ sets the transfer pattern of the phase shift mask to 1.
It is an image transferred when the exposure is transferred, and the same applies to the images I ₂ , I ₃ , and I ₄ . Image p _1a
~ P _1e are patterns transferred by the same exposure transfer, and images p _2a to p _2e and images p _3a ~.
The same applies to p _3e and images p _4a to p _4e . The images S ₁ , S ₂ , S ₃ , and S ₄ are images to which the light-shielding band pattern of the phase shift mask is transferred. As shown in FIG. 3, the repeated exposure transfer of the transfer pattern of the phase shift mask to the resist film by the exposure apparatus is performed without intervals. Therefore, the light-shielding band patterns of adjacent transfer images are duplicated and transferred. S ₁ in FIG.
₂ , S ₁₃ , S ₂₄ , and S ₃₄ are regions where the transferred images of the two light-shielding bands are overlapped and transferred, and S ₁₂₃₄ is a region where the transferred images of the four light-shielding bands are overlapped and transferred.

In recent years, due to the remarkable miniaturization of semiconductor devices, the transfer pattern of the phase shift film may be arranged near the light _- shielding band (image S1) as shown in the images _p1a to _p1d of FIG. It is increasing. The arrangement of a plurality of transfer patterns that are repeatedly transferred to the resist film on the semiconductor wafer has a positional relationship in which adjacent light-shielding band patterns overlap. The region where the light-shielding band patterns are overlapped and exposed and transferred is used as a cutting allowance when each chip is formed on the semiconductor wafer and then separated.

In such a case, when the fine pattern arranged in the vicinity of the light-shielding band is exposed and transferred to the resist film by the leakage light of the exposure light generated from the light-shielding band and the resist pattern is formed by the development process or the like. The phenomenon that the CD accuracy is lowered tends to occur, which has been a problem. In particular, the fine patterns arranged in the vicinity of the region _S1234 of the resist film that undergoes the exposure transfer of the light-shielding band pattern four times (patterns _p1d and p surrounded by a chain line circle in FIG. 3).
_2c , p3b, _p4a ) _tended to increase the integrated irradiation amount of leaked light, which was a particular problem.

As a method for solving these problems, it is conceivable to simply increase the film thickness of the light-shielding film to increase the optical density (OD) of the light-shielding band. However, if the film thickness of the light-shielding film is increased, it becomes necessary to increase the film thickness of the resist pattern (resist film) that serves as a mask when etching for forming a transfer pattern on the light-shielding film. Conventionally, the phase shift film is often formed of a material containing silicon, and the light-shielding film is formed of a material containing chromium (chromium-based material) having high etching selectivity with the phase shift film. In many cases. The light-shielding film made of a chrome-based material is patterned by dry etching with a mixed gas of chlorine-based gas and oxygen gas, but the resist film has low resistance to dry etching with a mixed gas of chlorine-based gas and oxygen gas. Therefore, when the film thickness of the light-shielding film is increased, it is necessary to significantly increase the film thickness of the resist film. However, when a fine pattern is formed on such a resist film, the problem of the resist pattern falling or missing tends to occur.

On the other hand, as disclosed in Patent Document 2, it is possible to reduce the thickness of the resist film by providing a hard mask film made of a silicon-containing material on a light-shielding film made of a chromium-based material. .. However, when the light-shielding film made of a chrome-based material is patterned by dry etching with a mixed gas of chlorine-based gas and oxygen gas, etching tends to proceed in the direction of the side wall of the pattern. Therefore, when dry etching using a hard mask film having a fine pattern as a mask is performed on the light-shielding film, the amount of side etching tends to be large if the film-shielding film is thick, and the fine particles formed on the light-shielding film. The CD accuracy of the pattern tends to decrease. The decrease in the CD accuracy of the fine pattern of the light-shielding film leads to a decrease in the CD accuracy of the fine pattern formed in the phase shift film by dry etching using the fine pattern of the light-shielding film as a mask, which becomes a problem. Further, a cleaning step is performed on the light-shielding film after patterning, but there is also a problem that if the film thickness of the light-shielding film is thick, the pattern of the light-shielding film tends to collapse during this cleaning.

In order to solve the above-mentioned problems, in the present invention, a phase shift film formed of a silicon-containing material and a light-shielding film including a layer formed of a chromium-containing material are laminated in this order on a translucent substrate. Regarding a mask blank having a structure, a phase shift mask manufactured from the mask blank is set in an exposure apparatus of a complicated illumination system to which SMO is applied, and is provided on a semiconductor wafer or the like which is an object to be transferred. Even when exposure transfer is performed on the resist film, the phase shift film and the phase shift film have a higher optical density than before so that the fine pattern formed on the resist film after the development process has high CD accuracy. The first object is to provide a mask blank having a laminated structure of films.
In addition to that, it is a second object of the present invention to provide a mask blank in which the CD accuracy of the fine pattern formed on the light-shielding film by dry etching is high and the occurrence of the light-shielding film pattern collapse is suppressed.

Further, the present invention relates to a phase shift mask manufactured by using this mask blank, and even when the phase shift mask is set in an exposure apparatus of a complicated illumination system and exposure transfer is performed on a resist film, the development is performed. It is possible to form a light-shielding band with a higher optical density than before so that the fine pattern formed on the resist film after treatment has high CD accuracy, and it is possible to form a fine pattern on the phase shift film with high accuracy. It is intended to provide a phase shift mask.
Another object of the present invention is to provide a method for manufacturing a semiconductor device using the phase shift mask.

The present invention has the following configuration as a means for solving the above problems.

(Structure 1)
A mask blank having a structure in which a phase shift film and a light-shielding film are laminated in this order on a translucent substrate.
The optical density of the ArF excimer laser in the laminated structure of the phase shift film and the light shielding film with respect to the exposure light is 3.5 or more.
The light-shielding film has a structure in which a lower layer and an upper layer are laminated from the translucent substrate side.
The lower layer is made of a material containing chromium and having a total content of chromium, oxygen, nitrogen and carbon of 90 atomic% or more.
The upper layer contains metal and silicon, and the total content of metal and silicon is 80 atomic%.
It consists of the above materials
A mask blank characterized in that the extinction coefficient k _U of the upper layer with respect to the exposure light is larger than the extinction coefficient k _L of the lower layer with respect to the exposure light.

(Structure 2)
The mask blank according to configuration 1, wherein the phase shift film has a transmittance of 1% or more with respect to the exposure light.
(Structure 3)
The mask blank according to the configuration 1 or 2, wherein the extinction coefficient k _L of the lower layer is 2.0 or less, and the extinction coefficient k _U of the upper layer is larger than 2.0.

(Structure 4)
The refractive index n _U of the upper layer with respect to the exposure light is the refractive index n of the lower layer with respect to the exposure light.
It is smaller than _L and is characterized in that the ratio n _U / n _L obtained by dividing the refractive index n _U of the upper layer with respect to the exposure light by the refractive index n _L of the lower layer with respect to the exposure light is 0.8 or more. The mask blank according to any one of 1 to 3.
(Structure 5)
The mask blank according to configuration 4, wherein the lower layer has a refractive index n _L of 2.0 or less, and the upper layer has a refractive index n _U smaller than 2.0.
(Structure 6)
The mask blank according to any one of configurations 1 to 5, wherein the lower layer is made of a material having a total content of chromium, oxygen and carbon of 90 atomic% or more.

(Structure 7)
The mask blank according to any one of configurations 1 to 6, wherein the upper layer is made of a material having a total content of tantalum and silicon of 80 atomic% or more.
(Structure 8)
The mask blank according to any one of configurations 1 to 7, wherein the phase shift film is made of a material containing silicon.

(Structure 9)
A phase shift mask having a structure in which a phase shift film having a transfer pattern and a light shielding film having a light shielding band pattern are laminated in this order on a translucent substrate.
The optical density of the ArF excimer laser in the laminated structure of the phase shift film and the light shielding film with respect to the exposure light is 3.5 or more.
The light-shielding film has a structure in which a lower layer and an upper layer are laminated from the translucent substrate side.
The lower layer is made of a material containing chromium and having a total content of chromium, oxygen, nitrogen and carbon of 90 atomic% or more.
The upper layer contains metal and silicon, and the total content of metal and silicon is 80 atomic%.
It consists of the above materials
A phase shift mask characterized in that the extinction coefficient k _U of the upper layer with respect to the exposure light is larger than the extinction coefficient k _L of the lower layer with respect to the exposure light.

(Structure 10)
The phase shift mask according to configuration 9, wherein the phase shift film has a transmittance of 1% or more with respect to the exposure light.
(Structure 11)
The phase shift mask according to the configuration 9 or 10, wherein the extinction coefficient k _L of the lower layer is 2.0 or less, and the extinction coefficient k _U of the upper layer is larger than 2.0.

(Structure 12)
The refractive index n _U of the upper layer with respect to the exposure light is the refractive index n of the lower layer with respect to the exposure light.
It is smaller than _L and is characterized in that the ratio n _U / n _L obtained by dividing the refractive index n _U of the upper layer with respect to the exposure light by the refractive index n _L of the lower layer with respect to the exposure light is 0.8 or more. The phase shift mask according to any one of 9 to 11.
(Structure 13)
The phase shift mask according to configuration 12, wherein the lower layer has a refractive index n _L of 2.0 or less, and the upper layer has a refractive index n _U smaller than 2.0.
(Structure 14)
The phase shift mask according to any one of configurations 9 to 13, wherein the lower layer is made of a material having a total content of chromium, oxygen and carbon of 90 atomic% or more.

(Structure 15)
The phase shift mask according to any one of configurations 9 to 14, wherein the upper layer is made of a material having a total content of tantalum and silicon of 80 atomic% or more.
(Structure 16)
The phases 9 to 15 are characterized in that the phase shift film is made of a material containing silicon.
The phase shift mask described in any of.

(Structure 17)
A method for manufacturing a semiconductor device, which comprises a step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate by using the phase shift mask according to any one of configurations 9 to 16.

Since the mask blank of the present invention has a high optical density suitable for SMO, which is 3.5 or more with respect to the exposure light of the ArF excima laser in the laminated structure of the phase shift film and the light shielding film, this mask blank is used. Even when the manufactured phase shift mask is set in an exposure device of a complicated illumination system to which SMO is applied and exposure transfer is performed on the resist film of the object to be transferred, the resist after the development process is performed. The CD accuracy of the fine pattern formed on the film can be increased.
Further, in the mask blank of the present invention, when a fine pattern is formed on a light-shielding film by dry etching, the CD accuracy of the formed fine pattern is high, and the fine pattern of the formed light-shielding film collapses due to cleaning or the like. Can be sufficiently suppressed.

The phase shift mask of the present invention is manufactured by using the mask blank of the present invention. Therefore, even when the phase shift mask is set in an exposure apparatus of a complicated illumination system to which SMO is applied and exposure transfer is performed on the resist film of the object to be transferred.
The CD accuracy of the fine pattern formed on the resist film after the development process can be improved.
Further, since the phase shift mask of the present invention manufactures a phase shift mask using the mask blank of the present invention, it is possible to form a fine pattern on the phase shift film with high accuracy.
Further, the method for manufacturing a semiconductor device using the phase shift mask of the present invention makes it possible to transfer a fine pattern to a resist film on a semiconductor wafer with good CD accuracy.

It is sectional drawing of the mask blank which concerns on embodiment of this invention. It is sectional drawing which shows the manufacturing process of the phase shift mask which concerns on embodiment of this invention. It is a schematic diagram which shows the arrangement of each transfer pattern when the transfer pattern of a phase shift mask is repeatedly exposed and transferred to a resist film.

First, the background to the completion of the present invention will be described. The present inventor sets a phase shift mask in an exposure apparatus of a complicated lighting system to which SMO is applied, and exposes and transfers it to a resist film provided on a semiconductor wafer or the like as an object to be transferred. Even if you do
We studied the optical density in the laminated structure of the phase shift film and the light-shielding film, which is necessary for the fine pattern formed on the resist film after the development process to have high CD accuracy. As a result, the optical density (hereinafter, simply referred to as optical density) with respect to the exposure light (hereinafter, referred to as ArF exposure light) of the ArF excimer laser in the laminated structure of the phase shift film and the light-shielding film is required to be 3.5 or more. I found out that.

Next, further research was conducted assuming that the transmittance of the phase shift film with respect to ArF exposure light is 6% (optical density of about 1.2), which is a widely used transmittance. In this case, the light-shielding film Ar
The optical density with respect to the F exposure light needs to be 2.3 or more. An attempt was made to form a light-shielding film having an optical density of 2.3 or more from a chromium-based material. When the optical density was increased to 2.3 or more by increasing the film thickness of the light-shielding film, it became necessary to significantly increase the thickness of the resist pattern, so that a fine pattern was formed on the light-shielding film by dry etching. It was difficult.
Further, a hard mask film made of a silicon-based material was provided on the light-shielding film, and an attempt was made to form a fine pattern on the light-shielding film by dry etching using the hard mask film on which the fine pattern was formed as a mask. However, it has been found that the amount of side etching generated when forming a fine pattern on the light-shielding film is large, and the CD accuracy of the fine pattern formed on the light-shielding film is low. Further, when cleaning is performed after the fine pattern is formed on the light-shielding film, a phenomenon that the pattern of the light-shielding film is detached occurs, and it is difficult to accurately form the fine pattern on the light-shielding film even with this method. rice field.

Thin films made of chromium-based materials tend to have higher optical densities per unit film thickness as the chromium content increases. Therefore, a light-shielding film is formed of a material having a significantly high chromium content such that the optical density is 2.3 or more, and a hard mask film of a silicon-based material is laminated on the light-shielding film.
It was confirmed whether it was possible to form a fine pattern on the light-shielding film. However, this light-shielding film has a very slow etching rate for dry etching with a mixed gas of chlorine-based gas and oxygen gas, resulting in low in-plane CD uniformity of the pattern formed on the light-shielding film.
As a result of these studies, it was found that it is practically difficult to form a light-shielding film having an optical density of 2.3 or more only with a chromium-based material.

Therefore, we tried to make the light-shielding film a laminated structure of a lower layer of a chromium-based material and an upper layer of a metal silicide-based material. By forming the lower layer arranged on the phase shift film side of the light-shielding film with a chrome-based material, it has high etching resistance to dry etching by fluorine-based gas performed when forming a fine pattern on the phase shift film. , Can have a function as a hard mask. In addition, since the phase shift film has high etching resistance against dry etching with a mixed gas of chlorine gas and oxygen gas performed when removing the light shielding film, the effect on the phase shift film when removing the light shielding film. Can be made smaller. On the other hand, by forming the upper layer of the light-shielding film with a metal silicide-based material, high etching resistance is achieved against dry etching by a mixed gas of chlorine-based gas and oxygen gas, which is performed when forming a fine pattern on the lower layer of the light-shielding film. It can have a function as a hard mask. In addition, the upper layer of the light-shielding film can be removed at the same time during dry etching with a fluorine-based gas, which is performed when forming a fine pattern on the phase shift film.

It is not preferable that the lower layer of the light-shielding film contains an element (such as silicon) that significantly lowers the etching rate for dry etching with a mixed gas of chlorine-based gas and oxygen gas. In consideration of this point, the lower layer of the light-shielding film is made of a material containing chromium and having a total content of chromium, oxygen, nitrogen and carbon of 90 atomic% or more. Due to the above circumstances, it is difficult to increase the chromium content in the chromium-based material forming the lower layer of the light-shielding film, and the lower layer A
There is a limit to increasing the extinction coefficient k _L (hereinafter, simply referred to as the extinction coefficient k _L ) with respect to the rF exposure light. In response to the above circumstances, it is effective to contain a large amount of oxygen in order to increase the etching rate for dry etching of a thin film of chromium-based material with a mixed gas of chlorine-based gas and oxygen gas, but oxygen causes the thin film to disappear. It becomes a factor that greatly lowers the coefficient k.

Conventionally, the upper layer of the light-shielding film has an extinction coefficient k higher than that of the lower layer in consideration of having an antireflection function.
Often uses small materials. However, with the recent improvement in the performance of the exposure apparatus, the restriction on the surface reflectance in the region outside the transfer pattern region (the region including the region where the light-shielding band is formed) has been relaxed. Therefore, the extinction coefficient k _U of the upper layer of the light-shielding film is changed to the extinction coefficient k _L of the lower layer.
I decided to make it larger than.

The upper layer of the light-shielding film is required to function as a hard mask when the lower layer of the chromium-based material is patterned by dry etching with a mixed gas of chlorine-based gas and oxygen gas. As the conventional hard mask film of a silicon-based material, an emphasis has been placed on enhancing the etching selectivity for a thin film of a chromium-based material, and a silicon material containing a relatively large amount of oxygen and nitrogen is used.
In the present invention, the oxygen and nitrogen contents of the upper layer of the metal silicide-based material are lower than before, and etching with respect to dry etching with a mixed gas of chlorine-based gas and oxygen gas between the lower layer of the chromium-based material. We verified the selectivity. As a result, even the upper layer of the metal silicide-based material that substantially does not contain oxygen and nitrogen (however, the surface layer in contact with the atmosphere is being oxidized) is dried by a mixed gas of chlorine-based gas and oxygen gas. It was found that the upper layer functions well as a hard mask when patterning the lower layer of the chromium-based material by etching. In order to suppress the increase in the overall film thickness of the light-shielding film due to laminating the upper layer, it is necessary to sufficiently increase the extinction coefficient _kU of the upper layer. From these studies, it was decided that the upper layer of the light-shielding film was made of a material containing metal and silicon, and the total content of metal and silicon was 80 atomic%.

As a result of the above diligent research, the mask blank of the present invention has been completed. In particular,
It is a mask blank having a structure in which a phase shift film and a light-shielding film are laminated in this order on a translucent substrate, and the optical density of the ArF excima laser in the laminated structure of the phase shift film and the light-shielding film is 3. The light-shielding film has a structure in which a lower layer and an upper layer are laminated from the translucent substrate side, and the lower layer contains chromium and has a total content of chromium, oxygen, nitrogen, and carbon of 9.
The upper layer is made of a material having 0 atomic% or more, the upper layer contains metal and silicon, and the total content of metal and silicon is 80 atomic% or more, and the extinction coefficient k with respect to the exposure light of the upper layer is k.
_U is characterized in that it is larger than the extinction coefficient k _L with respect to the exposure light of the lower layer.

Hereinafter, the detailed configuration of the present invention described above will be described with reference to the drawings. In each figure, similar components will be described with the same reference numerals.

<Mask blank>
FIG. 1 shows a schematic configuration of an embodiment of a mask blank. Mask blank 10 shown in FIG.
0 is a phase shift film 2, a lower layer 31 of the light shielding film 3 on one main surface of the translucent substrate 1.
And the upper layer 32 of the light-shielding film 3 are laminated in this order. The mask blank 100 may have a structure in which a resist film is laminated on the upper layer 32, if necessary. Further, for the above reason, the mask blank 100 is required to have an optical density of 3.5 or more with respect to ArF exposure light in a laminated structure of the phase shift film 2 and the light shielding film 3. Mask blank 1
00 is a laminated structure of the phase shift film 2 and the light shielding film 3, and the optical density with respect to the ArF exposure light is 3.
8 or more is more preferable, and 4.0 or more is further preferable. Hereinafter, the details of the main components of the mask blank 100 will be described.

[Translucent substrate]
The translucent substrate 1 is made of a material having good transparency to the exposure light used in the exposure process in lithography. As such a material, synthetic quartz glass, aluminosilicate glass, soda-lime glass, low thermal expansion glass (SiO ₂ -TiO ₂ glass, etc.), and various other glass substrates can be used. In particular, the substrate using synthetic quartz glass is ArF.
Since it has high transparency to exposure light, it can be suitably used as the translucent substrate 1 of the mask blank 100.

The exposure step in lithography referred to here is an exposure step in lithography performed by using a phase shift mask produced by using this mask blank 100, and the exposure light described below is ArF used in this exposure step. It is assumed that the exposure is an excimer laser (wavelength: 193 nm).

[Phase shift film]
The phase shift film 2 transmits ArF exposure light with an intensity that does not substantially contribute to exposure, and the transmitted ArF exposure light is the exposure light that has passed through the air at the same distance as the thickness of the phase shift film 2. It has a function of causing a predetermined phase difference between the two. Specifically, by patterning the phase shift film 2, a portion where the phase shift film 2 remains and a portion where the phase shift film 2 does not remain are formed, and the phase shift is performed with respect to the exposure light transmitted through the portion without the phase shift film 2. The phases of the light transmitted through the film 2 (light having an intensity that does not substantially contribute to the exposure) are substantially inverted. By doing so, the light sneaking into each other's region due to the diffraction phenomenon cancels each other out, the light intensity at the pattern boundary portion of the phase shift film 2 is set to almost zero, and the contrast, that is, the resolution at the pattern boundary portion is improved. A so-called phase shift effect can be obtained.

The phase shift film 2 preferably has a transmittance of 1% or more with respect to ArF exposure light, and more preferably 2% or more. Further, the phase shift film 2 has a transmittance of 35 for ArF exposure light.
% Or less is preferable, and 30% or less is more preferable. The phase shift film 2 preferably has the above phase difference of 150 degrees or more, and more preferably 160 degrees or more. Further, the phase shift film 2 preferably has the above phase difference of 200 degrees or less, and more preferably 190 degrees or less.

Here, it is assumed that such a phase shift film 2 is made of a material containing silicon (Si). Further, the phase shift film 2 is preferably formed of a material containing nitrogen (N) in addition to silicon. Such a phase shift film 2 can be patterned by dry etching using a fluorine-based gas, and has sufficient etching selectivity with respect to the lower layer 31 of the Cr-based material constituting the light-shielding film 3 described later.

The phase shift film 2 is preferably formed of a material made of silicon and nitrogen, or a material made of silicon and nitrogen containing one or more elements selected from metalloid elements and non-metal elements. The phase shift film 2 may contain any metalloid element in addition to silicon and nitrogen. Among these metalloid elements, boron (B), germanium (Ge), antimony (
It is preferable to contain one or more elements selected from Sb) and tellurium (Te) because it can be expected to increase the conductivity of silicon used as a sputtering target. The phase shift film 2 may contain any non-metal element in addition to silicon and nitrogen. Here, the non-metal element in the present invention is a non-metal element in a narrow sense (nitrogen (N), carbon (C), oxygen (O),
Phosphorus (P), sulfur (S), selenium (Se)), halogens and noble gases.
Among these non-metal elements, it is preferable to contain one or more elements selected from carbon, fluorine (F) and hydrogen (H).

The phase shift film 2 may contain a noble gas (also referred to as a noble gas; the same shall apply hereinafter in the present specification). The noble gas is an element that can increase the film forming speed and improve the productivity by being present in the film forming chamber when the phase shift film 2 is formed by reactive sputtering. When this noble gas turns into plasma and collides with the target, the target constituent elements pop out from the target, and on the way to reach the translucent substrate 1, the reactive gas is taken in and adheres to the translucent substrate 1 to transmit light. The phase shift film 2 is formed on the sex substrate 1. A small amount of noble gas in the film forming chamber is taken in until the target constituent element jumps out of the target and adheres to the translucent substrate 1. Preferred noble gases required for this reactive sputtering include argon (Ar), krypton (Kr), and xenon (Xe). Further, in order to relieve the stress of the phase shift film 2, helium (He) having a small atomic weight is used.
), Neon (Ne) can be positively incorporated into the phase shift film.

The phase shift film 2 may further contain a metal element as long as it can be patterned by dry etching using a fluorine-based gas. The metal elements contained include molybdenum (Mo), tungsten (W), titanium (Ti), tantalum (Ta), zirconium (Zr), hafnium (Hf), niobium (Nb), vanadium (V), and cobalt (Co).
), Chromium (Cr), Nickel (Ni), Ruthenium (Ru), Tin (Sn), Aluminum (Al).

The phase shift film 2 preferably has a thickness of 90 nm or less. If the thickness of the phase shift film 2 is thicker than 90 nm, the time required for patterning by dry etching with a fluorine-based gas becomes long. It is more preferable that the phase shift film 2 has a thickness of 80 nm or less. On the other hand, the phase shift film 2 preferably has a thickness of 40 nm or more. If the thickness of the phase shift film 2 is less than 40 nm, there is a possibility that the predetermined transmittance and phase difference required for the phase shift film cannot be obtained.

[Light-shielding film]
The light-shielding film 3 has a configuration in which the lower layer 31 and the upper layer 32 are laminated in this order from the phase shift film 2 side. The lower layer 31 contains chromium and has a total content of chromium, oxygen, nitrogen and carbon of 90.
It is made of a material that is at least atomic percent. The lower layer 31 is preferably formed of a material having a total content of chromium, oxygen, nitrogen and carbon of 95 atomic% or more, and more preferably formed of a material having a total content of 98 atomic% or more. This is an element other than the above (especially, in order to increase the etching rate for dry etching using a mixed gas of chlorine gas and oxygen gas.
This is because it is preferable to reduce the content of silicon).

The lower layer 31 may contain a metal element, a metalloid element, and a non-metal element other than the constituent elements as long as it satisfies the above range of total content. Examples of the metal element in this case include molybdenum, indium, and tin. In this case, the metalloid element is boron,
Germanium and the like can be mentioned. Examples of the non-metal element in this case include non-metal elements (phosphorus, sulfur, selenium) in a narrow sense, halogens (fluorine, chlorine, etc.), and noble gases (helium, neon, argon, krypton, xenon, etc.). In particular, the noble gas is an element that is slightly incorporated into the film when the lower layer 31 is formed into a film by a sputtering method, and is also an element that may be beneficial if it is positively contained in the layer. However, with respect to silicon, the content in the lower layer 31 is required to be 3 atomic% or less, preferably 1 atomic% or less, and more preferably 1 atomic% or less.

The lower layer 31 is preferably made of a material containing chromium and having a total content of chromium, oxygen and carbon of 90 atomic% or more. The lower layer 31 is preferably formed of a material having a total content of chromium, oxygen and carbon of 95 atomic% or more, and more preferably formed of a material having a total content of 98 atomic% or more. As the nitrogen content in the lower layer 31 increases, the etching rate for dry etching using a mixed gas of chlorine-based gas and oxygen gas increases, but the amount of side etching also increases. Considering that the etching rate for dry etching using a mixed gas of chlorine gas and oxygen gas is not faster than the case where the lower layer 31 contains oxygen, it can be said that it is preferable to reduce the nitrogen content in the lower layer 31. .. The lower layer 31 preferably has a nitrogen content of less than 10 atomic%, more preferably 5 atomic% or less, and even more preferably 2 atomic% or less. The lower layer 31 is substantially composed of chromium, oxygen and carbon, and includes an embodiment that is substantially free of nitrogen.

The lower layer 31 preferably has a chromium content of 50 atomic% or more. For the light-shielding film 3, a material having a high optical density is selected for the upper layer 32, but it is preferable to secure a certain degree of optical density even in the lower layer 31. This is also to suppress side etching that occurs when the lower layer 31 is patterned by dry etching. On the other hand, the lower layer 31 has a chromium content of 80.
It is preferably atomic% or less, and more preferably 75 atomic% or less. This is to ensure a sufficient etching rate when the light-shielding film 3 is patterned by dry etching.

The lower layer 31 preferably has an oxygen content of 10 atomic% or more, and more preferably 15 atomic% or more. This is to ensure a sufficient etching rate when the light-shielding film 3 is patterned by dry etching. On the other hand, the lower layer 31 preferably has an oxygen content of less than 50 atomic%, more preferably 40 atomic% or less, and even more preferably 35 atomic% or less. This is because it is preferable to secure a certain degree of optical density even in the lower layer 31 as described above. Further, this is to suppress side etching that occurs when the lower layer 31 is patterned by dry etching.

The lower layer 31 preferably has a carbon content of 10 atomic% or more. This is the lower layer 31
This is to suppress side etching that occurs when patterning by dry etching. On the other hand, the lower layer 31 preferably has a carbon content of 30 atomic% or less, more preferably 25 atomic% or less, and further preferably 20 atomic% or less. This is to ensure a sufficient etching rate when the light-shielding film 3 is patterned by dry etching. It is preferable that the difference in the content of each element constituting the lower layer 31 in the film thickness direction of the lower layer 31 is less than 10 atomic%. This is to reduce the variation in the etching rate in the film thickness direction when the lower layer 31 is patterned by dry etching.

The thickness of the lower layer 31 is preferably larger than 15 nm, more preferably 18 nm or more, and even more preferably 20 nm or more. On the other hand, the thickness of the lower layer 31 is preferably 60 nm or less, more preferably 50 nm or less, and further preferably 45 nm or less. For the light-shielding film 3, a material having a high optical density is selected for the upper layer 32, but there is a limit to increasing the contribution of the upper layer 32 to the optical density required for the entire light-shielding film 3. Therefore, it is necessary to secure a certain degree of optical density even in the lower layer 31. Further, since the lower layer 31 needs to increase the etching rate for dry etching using a mixed gas of chlorine-based gas and oxygen gas, there is a limit to improving the light-shielding performance. Therefore, the lower layer 31 needs to have a predetermined thickness or more. On the other hand, if the thickness of the lower layer 31 is too thick, it becomes difficult to suppress the occurrence of side etching. The thickness range of the lower layer 31 takes these constraints into account.

The upper layer 32 contains metal and silicon, and the total content of metal and silicon is 80 atomic%.
It is formed of the above materials. The upper layer 32 has a total content of metal and silicon of 85 atomic%.
It is preferably formed of the above-mentioned material, and more preferably formed of the material having 90 atomic% or more. Among the elements constituting the upper layer 32, metal and silicon are elements that enhance the light-shielding performance of the upper layer 32 with respect to ArF exposure light. Further, as described above, even if the total content of metal and silicon in the upper layer 32 is increased, high resistance to dry etching by a mixed gas of chlorine-based gas and oxygen gas performed when forming a fine pattern in the lower layer 31 is high. It has been found that it can function as a hard mask. On the other hand, since the surface of the upper layer 32 opposite to the phase shift film 2 is a surface that comes into contact with the atmosphere, the surface layer including the surface is likely to be oxidized. Therefore, it is difficult to form the entire upper layer 32 only with metal and silicon. On the other hand, it is desired that the upper layer 32 has a higher light-shielding performance than the lower layer 31. Considering these facts, the upper layer 32 is required to be formed of a material having a total content of metal and silicon of 80 atomic% or more in the average of the entire layer, and is preferably 85 atomic% or more. 90
It is more preferable that the content is atomic% or more.

The metal elements contained in the upper layer 32 are molybdenum (Mo), tungsten (W), titanium (Ti), tantalum (Ta), zirconium (Zr), hafnium (Hf), and niobium (N).
b), vanadium (V), cobalt (Co), chromium (Cr), nickel (Ni), ruthenium (Ru), rhodium (Rh), palladium (Pd), indium (In), tin (
It is preferable to select one or more metal elements from Sn) and aluminum (Al). Upper layer 3
The metal element contained in 2 is more preferably tantalum. Tantalum is an element that has a large atomic weight and high light-shielding performance, and is highly resistant to the cleaning liquid used in the cleaning process performed during the manufacturing of the phase shift mask from the mask blank and the cleaning liquid used in the cleaning performed on the phase shift mask. Is. The upper layer 32 has a total content of tantalum and silicon of 80.
It is preferably formed of a material having an atomic% or more, more preferably 85 atomic% or more, and further preferably 90 atomic% or more.

The upper layer 32 may contain a metalloid element and a non-metal element other than the constituent elements as long as it satisfies the above range of total content. Examples of the metalloid element in this case include boron and germanium. The non-metal element in this case is a non-metal element in a narrow sense (oxygen,
Nitrogen, carbon, phosphorus, sulfur, selenium), halogen (fluorine, chlorine, etc.), noble gas (helium,
Neon, argon, krypton, xenon, etc.). In particular, the noble gas is in the upper layer 3
It is an element that is slightly incorporated into the film when 2 is formed into a film by a sputtering method, and is also an element that may be beneficial if it is positively contained in the layer.

The upper layer 32 is a ratio obtained by dividing the metal content [atomic%] by the total metal and silicon content [atomic%] (that is, when the total metal and silicon content [atomic%] in the upper layer 32 is 100. The ratio of the metal content [atomic%] of the metal is expressed in [%]. Hereinafter, it is referred to as M / [M + Si] ratio), preferably 5% or more, and more preferably 10% or more. 15
% Or more is more preferable. Further, the upper layer 32 preferably has an M / [M + Si] ratio of 60% or less, more preferably 55% or less, and further preferably 50% or less. Thin films made of metal silicide-based materials often have a tendency for the light-shielding performance (optical density) to increase as the content ratio of metal and silicon approaches a stoichiometrically stable ratio. In the case of a thin film made of a metal silicide-based material, the ratio is stoichiometrically stable when the metal: silicon ratio is 1: 2, and the M / [M + Si] ratio of the upper layer 32 takes this tendency into consideration. It was done.

The thickness of the upper layer 32 is preferably 5 nm or more, more preferably 7 nm or more, and further preferably 10 nm or more. On the other hand, the thickness of the upper layer 32 is preferably 40 nm or less, more preferably 35 nm or less, and further preferably 30 nm or less. The contribution of the upper layer 32 to the optical density required for the entire light-shielding film 3 needs to be higher than the contribution of the lower layer 31. Further, there is a limit to increasing the optical density per unit film thickness of the upper layer 32. On the other hand, since the upper layer 32 needs to be capable of forming a fine pattern by dry etching using a resist film on which the fine pattern is formed as a mask, the upper layer 32 needs to be formed.
There is a limit to increasing the thickness of. The thickness range of the upper layer 32 takes these constraints into account. The thickness of the upper layer 32 is preferably thinner than the thickness of the lower layer 31.

The upper layer 32 forms a fine pattern by dry etching using a resist film on which a fine pattern is formed as a mask, but the surface of the upper layer 32 tends to have low adhesion to the resist film of an organic material. Therefore, it is preferable to apply HMDS (Hexamethyldisilazane) treatment on the surface of the upper layer 32 to improve the adhesion of the surface.

For the above reasons, the extinction coefficient k _U of the upper layer 32 of the light-shielding film 3 is required to be larger than the extinction coefficient k _L of the lower layer 31. The extinction coefficient k _L of the lower layer 31 is preferably 2.00 or less, more preferably 1.95 or less, and even more preferably 1.90 or less. Further, the extinction coefficient k _L of the lower layer 31 is preferably 1.20 or more, more preferably 1.25 or more, and further preferably 1.30 or more. On the other hand, the extinction coefficient _kU of the upper layer 32 is preferably larger than 2.00, more preferably 2.10 or more.
It is more preferably 2.20 or more. Further, the extinction coefficient k _U of the upper layer 32 is preferably 3.20 or less, more preferably 3.10 or less, and further preferably 3.00 or less.

The phase shift film 2 needs to have a function of transmitting the transmitted exposure light with a predetermined transmittance and a function of causing a predetermined phase difference. Since the phase shift film 2 is required to realize these functions with a thinner film thickness, the phase shift film 2 is often made of a material having a large refractive index n. On the other hand, the lower layer 31 of the light-shielding film 3 has a relatively high chromium content due to the above circumstances, and has a low nitrogen content, which is an element that tends to increase the refractive index n of the material when it is contained in the material. .. Therefore, the lower layer 31 has a refractive index n higher than that of the phase shift film 2.
Becomes smaller. On the other hand, as described above, the upper layer 32 of the light-shielding film 3 is required to significantly improve the light-shielding performance, and therefore the nitrogen content is desired to be lower than that of the lower layer 31. Due to these circumstances, the mask blank 100 has a laminated structure in which the refractive index n decreases in the order of the phase shift film 2, the lower layer 31, and the upper layer 32.

Generally, in a structure in which a film having a large refractive index n and a film having a small refractive index n are laminated, light passing through the inside of the film having a large refractive index n is the interface between the film having a large refractive index n and the film having a small refractive index. When the light is incident at a predetermined incident angle from a direction perpendicular to the interface, the light enters the film having a small refractive index n from the interface at an emission angle larger than the incident angle. Further, the larger the difference in refractive index between the film having a large refractive index n and the film having a small refractive index n, the larger the difference between the incident angle and the emitted angle.
Therefore, the exposure light traveling tilted at a predetermined angle from the direction perpendicular to the interface of the phase shift film 2 enters the lower layer 31 of the light shielding film 2 from the phase shift film 2 with respect to the interface. The tilt angle from the vertical direction will increase. Further, the exposure light that has penetrated into the lower layer 31 is
When invading the upper layer 32, the inclination angle from the direction perpendicular to the interface becomes larger.

When a light-shielding band is formed on such a light-shielding film 3, when the exposure light whose irradiation angle is complicated by SMO travels from the lower layer 31 to the upper layer 32, the inclination angle from the direction perpendicular to the interface increases. As a result, a phenomenon in which the light amount is not sufficiently attenuated from the side wall of the upper layer 32 on which the light-shielding band is formed and is emitted as leaked light is likely to occur. In order to reduce the leakage light caused by this phenomenon, the refractive index n _U of the upper layer 32 is smaller than the refractive index n _L of the lower layer 31 (that is,).
The ratio n _U / n _L obtained by dividing the refractive index n _U of the upper layer 32 by the refractive index n _L of the lower layer 31 is less than 1.0).
It is preferable that the ratio n _U / n _L obtained by dividing the refractive index n _U of the upper layer 32 by the refractive index n _L of the lower layer 31 is 0.8 or more. The ratio n _U / n _L obtained by dividing the refractive index n _U of the upper layer 32 by the refractive index n _L of the lower layer 31 is more preferably 0.85 or more, and further preferably 0.9 or more.

For the above reasons, the refractive index n _L of the lower layer 31 is preferably 2.00 or less.
It is more preferably 98 or less, and further preferably 1.95 or less. In addition, the lower layer 31
The refractive index n _L is preferably 1.45 or more, more preferably 1.50 or more, and further preferably 1.55 or more. On the other hand, the refractive index n _U of the upper layer 32 is 2.
It is preferably smaller than 00, more preferably 1.95 or less, and even more preferably 1.90 or less. Further, the refractive index n _U of the upper layer 32 is preferably 1.30 or more, more preferably 1.35 or more, and further preferably 1.40 or more.

In the exposure process in lithography, it is desired that the surface reflectance of the exposure light on both main surfaces of the phase shift mask is not too high in order to prevent the defect of the exposure transfer due to the reflection of the ArF exposure light. In particular, the reflectance of the surface side (the surface farthest from the translucent substrate) of the light-shielding film to which the reflected light of the exposure light from the reduction optical system of the exposure apparatus hits is, for example, 60% or less (preferably 55%). The following) is desired. This is to suppress stray light generated by multiple reflections between the surface of the light-shielding film and the lens of the reduction optical system.

The thickness of the light-shielding film 3 in the laminated structure of the lower layer 31 and the upper layer 32 is preferably 80 nm or less, more preferably 75 nm or less, and further preferably 70 nm or less. Further, the thickness of the light-shielding film 3 in the laminated structure of the lower layer 31 and the upper layer 32 is preferably 30 nm or more, more preferably 35 nm or more, and further preferably 40 nm or more. If the overall film thickness of the light-shielding film 3 is too thick, it becomes difficult to form a fine pattern on the light-shielding film 3 with high accuracy. On the other hand, if the overall film thickness of the light-shielding film 3 is too thin, it becomes difficult for the light-shielding film 3 to satisfy the required optical density.

The lower layer 31 and the upper layer 32 of the phase shift film 2 and the light shielding film 3 can be formed by a sputtering method. The sputtering may be a direct current (DC) power source or a high frequency (RF) power source, and may be a magnetron sputtering method or a conventional method. DC sputtering is preferable because the mechanism is simple. Further, it is preferable to use a magnetron because the film formation rate becomes faster and the productivity is improved. The film forming apparatus may be an in-line type or a single-wafer type.

[Resist film]
In the mask blank 100, it is preferable that the resist film of the organic material is formed with a film thickness of 100 nm or less in contact with the surface of the upper layer 32 of the light-shielding film 3. In this case, the upper layer 32
It is preferable to apply the HMDS treatment on the surface of the surface and then apply and form the resist film.
The upper layer 32 is made of a material capable of patterning a fine pattern by dry etching with fluorine gas. Since the upper layer 32 functions as a hard mask during dry etching with a mixed gas of chlorine-based gas and oxygen gas performed when patterning a fine pattern on the lower layer 31, the resist film is a light-shielding film 3 even if it is 100 nm or less. It is possible to form a fine pattern. It is more preferable that the resist film has a film thickness of 80 nm or less. The resist film is preferably a resist for electron beam writing exposure, and more preferably a chemically amplified resist.

The mask blank 100 as described above is Ar in a laminated structure of the phase shift film 2 and the light shielding film 3.
The optical density of the F excimer laser with respect to the exposure light is 3.5 or more, which is a high optical density suitable for SMO. Therefore, the phase shift mask manufactured from the mask blank 100 is S.
Even when the resist film of the object to be transferred is exposed and transferred by setting it in an exposure device of a complicated lighting system to which MO is applied, a fine pattern formed on the resist film after the development process. CD accuracy can be increased. Further, the mask blank 100 is a light-shielding film 3.
On the other hand, when a fine pattern is formed by dry etching, the CD accuracy of the formed fine pattern is high, and it is possible to sufficiently prevent the fine pattern of the formed light-shielding film 3 from collapsing due to cleaning or the like.

<Manufacturing method of mask blank>
The mask blank 100 having the above configuration is manufactured by the following procedure. First, the translucent substrate 1 is prepared. In this translucent substrate 1, the end face and the main surface are polished to a predetermined surface roughness (for example, the root mean square roughness Rq is 0.2 nm or less in the inner region of a quadrangle having a side of 1 μm), and then the predetermined surface roughness is determined. It has been washed and dried.

Next, a phase shift film 2 is formed on the translucent substrate 1 by a sputtering method.
After forming the phase shift film 2, an annealing treatment is performed at a predetermined heating temperature as a post-treatment. Next, the lower layer 31 of the light-shielding film 3 is formed on the phase-shift film 2 by a sputtering method. Then, the upper layer 32 of the light-shielding film 3 is formed on the lower layer 31 by a sputtering method. In the film formation of each layer by the sputtering method, a sputtering target and a sputtering gas containing the materials constituting each layer in a predetermined composition ratio are used, and if necessary, a mixed gas of the above-mentioned noble gas and a reactive gas is sputtered. A film is formed using it as a gas. After that, when the mask blank 100 has a resist film, the upper layer 3 is necessary.
The surface of 2 is subjected to HMDS treatment. Then, a resist film is formed on the surface of the upper layer 32 treated with HMDS by a coating method such as a spin coating method, and the mask blank 10 is formed.
Complete 0.

<Manufacturing method of phase shift mask and phase shift mask>
Next, a method of manufacturing a halftone type phase shift mask using the mask blank 100 having the configuration shown in FIG. 1 will be described with reference to a schematic cross-sectional view showing a manufacturing process of the phase shift mask of FIG.

First, the surface of the upper layer 32 of the light-shielding film 3 in the mask blank 100 is subjected to the HMDS treatment. Next, a resist film is formed on the upper layer 32 after the HMDS treatment by a spin coating method. Next, with respect to the resist film, the first pattern to be formed on the phase shift film 2 (
The phase shift pattern (phase shift pattern, transfer pattern) is exposed and drawn with an electron beam. After that, the resist film is subjected to predetermined treatments such as PEB (post-exposure baking) treatment, development treatment, and post-baking treatment.
A first pattern (phase shift pattern) (resist pattern 4a) is formed on the resist film (see FIG. 2A). The first pattern drawn by exposure is a pattern optimized by applying SMO.

Next, using the resist pattern 4a as a mask and using a fluorine-based gas, the upper layer 3 of the light-shielding film 3 is used.
The dry etching of No. 2 is performed to form a first pattern (upper layer pattern 32a) on the upper layer 32 (see FIG. 2B). After that, the resist pattern 4a is removed (see FIG. 2C).
.. Here, the lower layer 31 of the light-shielding film 3 is left without removing the resist pattern 4a.
You may perform dry etching of. In this case, the resist pattern 4a disappears during the dry etching of the lower layer 31.

Next, using the upper layer pattern 32a as a mask, high-bias etching using a mixed gas of chlorine-based gas and oxygen gas is performed to form a first pattern (lower layer pattern 31a) in the lower layer 31 (see FIG. 2D). ). For dry etching on the lower layer 31, an etching gas having a higher mixing ratio of chlorine-based gas than before is used. The mixing ratio of the mixed gas of the chlorine-based gas and the oxygen gas in the dry etching of the lower layer 31 is the gas flow rate ratio in the etching apparatus (chamber), and it is preferable that the chlorine-based gas: oxygen gas = 10 or more: 1. , 15 or more: 1 is more preferable, and 20 or more: 1 is more preferable. By using an etching gas having a high mixing ratio of chlorine-based gas, the anisotropy of dry etching can be enhanced. Further, in the dry etching of the lower layer 31, the mixing ratio of the mixed gas of the chlorine-based gas and the oxygen gas is the gas flow rate ratio in the etching apparatus (chamber), and the chlorine-based gas: oxygen gas = 40.
Below, it is preferably 1.

Further, in the dry etching of the lower layer 31, the bias voltage applied from the back surface side of the translucent substrate 1 is also made higher than before. There is a difference in the effect of increasing the bias voltage depending on the etching apparatus, but for example, the electric power when applying this bias voltage is preferably 15 [W] or more, more preferably 20 [W] or more, and 30. It is more preferable that it is [W] or more. By increasing the bias voltage, the anisotropy of dry etching with a mixed gas of chlorine-based gas and oxygen gas can be increased.

Next, a resist film is formed on the upper layer pattern 32a and the phase shift film 2 by a spin coating method. A second pattern (a pattern including a light-shielding band pattern) to be formed on the light-shielding film 3 is exposed and drawn on the resist film with an electron beam. After that, a predetermined process such as a developing process is performed to form a resist film having a second pattern (light-shielding pattern) (resist pattern 5b) (see FIG. 2 (e)).

Subsequently, dry etching using a fluorine-based gas is performed to form a first pattern (phase shift pattern 2a) on the phase shift film 2 using the lower layer pattern 31a as a mask, and to form the upper layer pattern 32a using the resist pattern 5b as a mask. A second pattern (upper layer pattern 32b) is formed (see FIG. 2 (f)). After that, the resist pattern 5b is removed. Here, the light-shielding film 3 described later will be described while the resist pattern 5b is not removed and remains.
Dry etching of the lower layer pattern 31a may be performed. In this case, the resist pattern 5b disappears during the dry etching of the lower layer pattern 31a.

Next, using the upper layer pattern 32b as a mask, dry etching is performed using a mixed gas of chlorine-based gas and oxygen gas, and a second pattern (lower layer pattern 31b) is applied to the lower layer pattern 31a.
(See FIGS. 2 (g) and 2 (h)). The dry etching of the lower layer pattern 31a at this time may be performed under the conventional conditions for the mixing ratio of the chlorine-based gas and the oxygen gas and the bias voltage. Finally, a phase shift mask 200 is obtained through a predetermined process such as cleaning (FIG. 2 (FIG. 2).
h) See).

The chlorine-based gas used in the dry etching during the above manufacturing process is not particularly limited as long as it contains Cl. For example, as chlorine-based gas, Cl ₂ , SiH ₂ Cl ₂
, CHCl ₃ , CH ₂ Cl ₂ , CCl ₄ , BCl ₃ , and the like. Further, the fluorine-based gas used in the dry etching during the above manufacturing process is not particularly limited as long as F is contained. For example, as fluorine-based gas, CHF ₃ , CF ₄ , C ₂ F ₆ , C ₄ F ₈ , S
_F6 etc. can be mentioned. In particular, since the fluorine-based gas containing no C has a relatively low etching rate with respect to the glass substrate, damage to the glass substrate can be further reduced.

In the phase shift mask 200 manufactured by the above steps, a phase shift film having a transfer pattern (phase shift pattern 2a) and a light shielding film having a light shielding pattern (light shielding pattern 3b) are arranged in this order on the translucent substrate 1. It has a laminated structure (see FIG. 2 (h)). Since this phase shift mask is manufactured from the mask blank 100, it has the same characteristics as the mask blank 100. That is, the phase shift mask 200 is a phase shift mask having a structure in which a phase shift film 2 having a transfer pattern and a light shielding film 3 having a light shielding band pattern are laminated in this order on a translucent substrate 1. ArF in a laminated structure of shift film 2 and light-shielding film 3
The optical density of the excimer laser with respect to the exposure light is 3.5 or more, the light-shielding film 3 has a structure in which the lower layer 31 and the upper layer 32 are laminated from the translucent substrate 1 side, and the lower layer 31 contains chromium. The upper layer 32 is composed of a material having a total content of chromium, oxygen, nitrogen and carbon of 90 atomic% or more, and the upper layer 32 contains metal and silicon, and the total content of metal and silicon is 80 atomic%.
It is made of the above-mentioned materials, and is characterized in that the extinction coefficient k _U for the exposure light of the upper layer 32 is larger than the extinction coefficient k _L for the exposure light of the lower layer 31.

The phase shift mask 200 is manufactured by using the mask blank 100. Therefore, even when the phase shift mask 200 is set in an exposure apparatus of a complicated lighting system to which SMO is applied and exposure transfer is performed on the resist film of the object to be transferred, the development process is performed. It is possible to increase the CD accuracy of the fine pattern formed on the resist film later.

<Manufacturing method of semiconductor device>
Next, a method of manufacturing a semiconductor device using the above-mentioned phase shift mask 200 will be described. The method for manufacturing a semiconductor device is characterized in that the transfer pattern (phase shift pattern 2a) of the phase shift mask 200 is exposed and transferred to the resist film on the semiconductor substrate by using the above-mentioned phase shift mask 200. The manufacturing method of such a semiconductor device is
Do the following:

First, a substrate on which a semiconductor device is formed is prepared. This substrate may be, for example, a semiconductor substrate, a substrate having a semiconductor thin film, or a microfabricated film may be formed on top of the semiconductor thin film. Then, a resist film is formed on the prepared substrate, and the resist film is repeatedly subjected to reduced transfer exposure using the above-mentioned phase shift mask 200.
As a result, the transfer pattern formed on the phase shift mask 200 is arranged without a gap with respect to the resist film. The exposure apparatus used at this time is capable of irradiating the phase shift mask 200 to which the SMO is applied and the phase shift pattern 2a is optimized with ArF exposure light with an optimum illumination system.

Further, the resist film on which the transfer pattern is exposed and transferred is developed to form a resist pattern, the surface layer of the substrate is etched using this resist pattern as a mask, and impurities are introduced. .. After the processing is completed, the resist pattern is removed. The above processing is repeated on the substrate while exchanging the transfer mask, and further necessary processing is performed to complete the semiconductor device.

The manufacturing of the semiconductor device as described above uses an exposure apparatus capable of irradiating the phase shift mask 200 to which the SMO is applied and the phase shift pattern 2a is optimized with ArF exposure light in a complicated but optimum lighting system. Therefore, since the exposure transfer is repeated to the resist film on the semiconductor substrate, the fine pattern can be exposed and transferred to the resist film with high accuracy. Further, the phase shift mask 200 has a light-shielding pattern in which the optical density with respect to ArF exposure light in the laminated structure of the phase-shift pattern 2a and the light-shielding pattern 3b constituting the light-shielding band is 3.5 or more, which is significantly higher than the conventional one. The extinction coefficient k _U of the upper layer pattern 32b of 3b is larger than the extinction coefficient k _L of the lower layer pattern 31b, and the configuration is such that the light leaking from the light shielding zone is sufficiently suppressed. As a result, even if the phase shift mask 200 is irradiated with ArF exposure light in a complicated lighting system, it is sufficiently suppressed that the CD accuracy of the fine pattern exposed and transferred to the resist film on the semiconductor substrate is lowered due to the leakage light. can do. Therefore, when the circuit pattern is formed by dry etching the lower layer film using this resist film pattern as a mask, it is possible to form a highly accurate circuit pattern without wiring short circuit or disconnection due to insufficient accuracy.

Hereinafter, embodiments of the present invention will be described in more detail with reference to Examples.

(Example 1)
[Manufacturing of mask blank]
With reference to FIG. 1, the dimensions of the main surface are about 152 mm × about 152 mm, and the thickness is about 6.35 mm.
A translucent substrate 1 made of synthetic quartz glass of No. 1 was prepared. The end face and the main surface of the translucent substrate 1 are polished to a predetermined surface roughness (Rq of 0.2 nm or less), and then subjected to a predetermined cleaning treatment and a drying treatment.

Next, the translucent substrate 1 is installed in the single-wafer DC sputtering apparatus, and a mixed sintering target (Mo: Si = 11 atomic%: 89 atomic%) of molybdenum (Mo) and silicon (Si) is used. , A phase shift consisting of molybdenum, silicon and nitrogen on the translucent substrate 1 by reactive sputtering (DC sputtering) using a mixed gas of argon (Ar), nitrogen (N ₂ ) and helium (He) as the sputtering gas. The film 2 was formed with a thickness of 69 nm.

Next, the translucent substrate 1 on which the phase shift film 2 was formed was heat-treated to reduce the film stress of the phase shift film 2 and to form an oxide layer on the surface layer. Specifically, using a heating furnace (electric furnace), the heating temperature is 450 ° C. and the heating time is 1 hour in the atmosphere.
Heat treatment was performed. When the transmittance and phase difference of the phase shift film 2 after heat treatment with respect to light having a wavelength of 193 nm were measured using a phase shift amount measuring device (MPM193 manufactured by Lasertec), the transmittance was 6.0% and the phase difference was high. It was 177.0 degrees (deg).

Next, a translucent substrate 1 having a phase shift film 2 formed therein is installed in a single-wafer DC sputtering apparatus, and an argon (Ar), carbon dioxide (CO ₂ ) and helium are used using a chromium (Cr) target. Reactive sputtering (DC sputtering) was performed in the mixed gas atmosphere of (He). As a result, a light-shielding film made of chromium, oxygen, and carbon (which is in contact with the phase shift film 2).
The lower layer 31 of the CrOC film) 3 was formed with a film thickness of 43 nm.

Next, a translucent substrate 1 on which the phase shift film 2 and the lower layer 31 are laminated is installed in a single-wafer DC sputtering apparatus, and an argon (A) is used using a tantalum silicide (TaSi ₂ ) target.
r) Using the gas as a sputtering gas, an upper layer 32 of the light-shielding film 3 made of tantalum and silicon was formed on the lower layer 31 of the light-shielding film 3 by DC sputtering to a thickness of 8 nm.

Next, the translucent substrate 1 on which the lower layer (CrOC film) 31 and the upper layer (TaSi film) 32 were formed was heat-treated. Specifically, a hot plate was used to perform heat treatment in the atmosphere at a heating temperature of 280 ° C. and a heating time of 5 minutes. After heat treatment, a spectrophotometer (Cary4000 manufactured by Azilent Technology Co., Ltd.) is used for the translucent substrate 1 in which the phase shift film 2 and the light shielding film 3 are laminated, and the ArF excimer having a laminated structure of the phase shift film 2 and the light shielding film 3 is used. When the optical density at the wavelength of the laser light (about 193 nm) was measured, it was 4.12.
Met. Further, when the surface reflectance of the light-shielding film 3 on the opposite side of the phase shift film 2 was measured, it was found.
It was 51%. Finally, a predetermined cleaning treatment was performed to produce the mask blank 100 of Example 1.

A mask blank in which the phase shift film 2 and the light-shielding film 3 were laminated on the main surface of another translucent substrate 1 under the same conditions was manufactured. The phase shift film 2 and the light-shielding film 3 of the mask blank were analyzed by X-ray photoelectron spectroscopy (XPS) (with RBS correction). As a result, the composition of the internal region excluding the surface layer (the region from the surface opposite to the translucent substrate 1 to the depth of 3 nm) where the phase shift film 2 is being oxidized is Mo: 6 atomic%, Si. : 45 atomic%, N: 49 atomic%. The composition of the lower layer 31 of the light-shielding film 3 is Cr: 71 atomic%, O: 15 atomic%, C: 14 atomic%, which is the opposite of the surface layer (opposite to the translucent substrate 1) in which the upper layer 32 is being oxidized. 3n from the side surface
The composition of the internal region excluding the region up to the depth of m) is Ta: 32 atomic%, Si: 68 atomic%.
Met. It was confirmed that the difference between the constituent elements in the thickness direction of the lower layer 31 was 3 atomic% or less, and there was substantially no composition gradient in the thickness direction. Further, it was confirmed that the difference between the constituent elements in the thickness direction in the inner region of the upper layer 32 was 3 atomic% or less, and there was substantially no composition gradient in the thickness direction in the inner region. Furthermore, it was also confirmed that the total content of tantalum (Ta) and silicon (Si) in the entire upper layer 32 was 80 atomic% or more.

The refractive index n and the extinction coefficient k of the light having a wavelength of 193 nm in the lower layer 31 and the upper layer 32 of the light-shielding film 3 were measured using a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam). As a result, the refractive index n _L of the lower layer 31 at a wavelength of 193 nm is 1.82 and the extinction coefficient k _L is 1.83, and the refractive index n _U of the upper layer 32 at a wavelength of 193 nm is 1.78 and the extinction coefficient k _U. Was 2.84. Further, the ratio n _U / n _L obtained by dividing the refractive index n _U at the wavelength 193 nm of the upper layer 32 by the refractive index n _L at the wavelength 193 nm of the lower layer 31 was 0.978.

[Manufacturing of phase shift mask]
Next, using the mask blank 100 of Example 1, the halftone type phase shift mask 200 of Example 1 was manufactured by the following procedure. First, HM on the surface of the upper layer 32 of the light-shielding film 3
DS processing was applied. Subsequently, a resist film made of a chemically amplified resist for electron beam writing was formed with a film thickness of 100 nm in contact with the surface of the upper layer 32 by a spin coating method. Next, a first pattern, which is a phase shift pattern to be formed on the phase shift film 2, is drawn with an electron beam on the resist film, subjected to a predetermined development process and a cleaning process, and a resist having the first pattern is performed. A pattern 4a was formed (see FIG. 2A). The first pattern drawn by this exposure was a pattern optimized by applying SMO. The first pattern is p in FIG.
As shown in _1a to _p1d , it has a fine pattern in the vicinity of the light-shielding zone.

Next, using the resist pattern 4a as a mask, dry etching using a fluorine-based gas (SF ₆ + He) is performed on the upper layer 32, and the first pattern (upper layer pattern 32) is applied to the upper layer 32.
a) was formed (see FIG. 2 (b)). Next, the resist pattern 4a was removed (FIG. 2 (c).
)reference). Subsequently, using the upper layer pattern 32a as a mask, chlorine gas (Cl ₂ ) and oxygen gas (Cl 2) and oxygen gas (Cl 2) are used.
Dry etching using a mixed gas of O ₂ ) (gas flow rate ratio Cl ₂ : O ₂ = 13: 1)
High bias etching with a power of 50 [W] when a bias voltage is applied) was performed on the lower layer 31 to form a first pattern (lower layer pattern 31a) on the lower layer 31 (FIG. 2 (d)).
reference).

Next, a resist film was formed on the upper layer pattern 32a and the phase shift film 2 by a spin coating method. A second pattern (a pattern including a light-shielding band pattern) to be formed on the light-shielding film 3 was exposed and drawn on the resist film with an electron beam. After that, a predetermined process such as a developing process was performed to form a resist film (resist pattern 5b) having a second pattern (light-shielding pattern) (see FIG. 2 (e)).

Next, dry etching is performed using a fluorine-based gas (SF ₆ + He) to form a first pattern (phase shift pattern 2a) on the phase shift film 2 using the lower layer pattern 31a as a mask, and mask the resist pattern 5b. A second pattern (upper layer pattern 32b) was formed on the upper layer pattern 32a (see FIG. 2 (f)). Then, the resist pattern 5b was removed (see FIG. 2 (g)). Next, using the upper layer pattern 32b as a mask, dry etching is performed using a mixed gas of chlorine gas (Cl ₂ ) and oxygen gas (O ₂ ) (gas flow ratio Cl ₂ : O ₂ = 4: 1), and the lower layer pattern is performed. A second pattern in 31a (lower layer pattern 31)
b) was formed (see FIGS. 2 (g) and 2 (h)). Finally, a phase shift mask 200 of Example 1 was obtained through a predetermined treatment such as cleaning (see FIG. 2 (h)).

The mask inspection device (KLA-Tenco) is used for the phase shift mask 200 of the first embodiment.
When a mask inspection was performed with a Teron 600 Series manufactured by r Co., Ltd., no defect was found in the phase shift pattern 2a. For this reason, the light-shielding film 3 having higher light-shielding performance than the conventional one.
Even so, it was confirmed that the fine pattern of the resist pattern 4a sufficiently functions as a hard mask for forming the phase shift film 2. Further, even if the total content of metal and silicon in the upper layer 32 is increased, it has high resistance to dry etching by a mixed gas of chlorine-based gas and oxygen gas performed when forming a fine pattern in the lower layer 31. It was confirmed that it functions as a hard mask. Further, the CD accuracy of the fine pattern formed on the light-shielding film 3 is lowered, and the CD accuracy of the fine pattern formed on the phase shift film 2, which has been a concern due to the light-shielding film 3 having higher light-shielding performance than the conventional one. The problem of deterioration of the light-shielding film and the problem of the occurrence of pattern collapse of the light-shielding film 3 are not a problem at all, and the CD accuracy of these fine patterns is high, and the light-shielding film 3
It was confirmed that the occurrence of pattern collapse can be suppressed.

[Evaluation of pattern transfer performance]
The phase shift mask 20 of the first embodiment is applied to the mask stage of the exposure apparatus capable of irradiating the phase shift mask 200 with ArF exposure light in an illumination system optimized by SMO.
0 was set, and repeated exposure transfer was performed on the resist film on the semiconductor substrate in the arrangement shown in FIG. The resist film on the semiconductor substrate after exposure transfer is subjected to development processing, etc.
A resist pattern was formed. When the resist pattern was observed by SEM, it had a high C.
It was confirmed that the resist pattern was formed with D accuracy. The fine patterns p _1d , p _2c , p _3b , and p _4a in the vicinity of the image S ₁₂₃₄ in the region where the light-shielding band shown in FIG. It was confirmed that it was formed. From this result, it can be said that the circuit pattern can be formed with high accuracy by dry etching using this resist pattern as a mask.

(Example 2)
[Manufacturing of mask blank]
In the mask blank 100 of Example 2, the thickness of the lower layer 31 of the light-shielding film 3 was formed at 18 nm.
It was manufactured by the same procedure as in Example 1 except that the thickness of the upper layer 32 was formed to be 24 nm. For the mask blank 100 of Example 2, a spectrophotometer (Cary 4000 manufactured by Azilent Technology Co., Ltd.) was used, and the optical concentration at the light wavelength (about 193 nm) of the ArF excimer laser having a laminated structure of the phase shift film 2 and the light shielding film 3. As a result of measuring 4.12
Met. Further, when the surface reflectance of the light-shielding film 3 on the opposite side of the phase shift film 2 was measured, it was found.
It was 55%.

[Manufacturing of phase shift mask]
Next, using the mask blank 100 of Example 2, the phase shift mask 200 of Example 2 was manufactured by the same procedure as that of Example 1. Similar to the case of the first embodiment, the mask inspection device (Teron 6 manufactured by KLA-Tencor) is used for the phase shift mask 200 of the second embodiment.
When the mask inspection was performed with 00Series), no defect was found in the phase shift pattern 2a. From this, it was confirmed that the same as in Example 1.

[Evaluation of pattern transfer performance]
Similar to the case of the first embodiment, the phase shift mask 200 of the second embodiment is provided on the mask stage of the exposure apparatus capable of irradiating the phase shift mask 200 with ArF exposure light in the illumination system optimized by SMO. Was set, and repeated exposure transfer was performed on the resist film on the semiconductor substrate in the arrangement shown in FIG. The resist film on the semiconductor substrate after exposure transfer was subjected to development processing and the like to form a resist pattern. The resist pattern is SEM
It was confirmed that the resist pattern was formed with high CD accuracy. Image S of the region where the light-shielding band shown in FIG. 3 was exposed and transferred four times, which was a concern for deterioration of CD accuracy.
It was confirmed that the fine patterns p _1d , p _2c , p _3b , and p _4a in the vicinity of ₁₂₃₄ were also formed with high CD accuracy. From this result, it can be said that the circuit pattern can be formed with high accuracy by dry etching using this resist pattern as a mask.

(Example 3)
[Manufacturing of mask blank]
The mask blank 100 of Example 3 was manufactured by the same procedure as that of Example 1 except for the light-shielding film 3. In the light-shielding film 3 of Example 3, the lower layer 32 is formed of a CrOCN film, and the upper layer 31 has the same composition as that of Example 1 and the film thickness is changed. Specifically, a translucent substrate 1 on which a phase shift film 2 is formed is installed in a single-wafer DC sputtering apparatus, and an argon (Ar) and carbon dioxide (CO ₂ ) are used using a chromium (Cr) target. , Nitrogen (N ₂ ) and helium (He) were subjected to reactive sputtering (DC sputtering) in a mixed gas atmosphere. As a result, the lower layer 31 of the light-shielding film (CrOCN film) 3 made of chromium, oxygen, carbon and nitrogen was formed with a film thickness of 43 nm in contact with the phase shift film 2. Next, in the single-wafer DC sputtering apparatus, a translucent substrate 1 in which the lower layer 31 of the phase shift film 2 and the light-shielding film 3 is laminated is installed, and an argon (Ar) is used using a tantalum silicide (TaSi ₂ ) target. The gas is a sputtering gas, and D
The upper layer 32 of the light-shielding film 3 made of tantalum and silicon was formed on the lower layer 31 of the light-shielding film 3 by C sputtering to a thickness of 12 nm.

Similar to the first embodiment, the phase shift film 2 and the light shielding film 3 are placed on the main surface of another translucent substrate 1 under the same conditions.
Manufactured a laminated mask blank. The lower layer 31 and the upper layer 32 of the light-shielding film 3 of the mask blank of Example 3 were analyzed by X-ray photoelectron spectroscopy (with XPS and RBS correction). As a result, the composition of the lower layer 31 is Cr: 55 atomic%, O: 22 atomic%, C: 12 atomic%,
N: It was 11 atomic%. Further, it was confirmed that the difference between the constituent elements in the thickness direction in the inner region of the lower layer 31 was 3 atomic% or less, and there was substantially no composition gradient in the thickness direction in the inner region. The upper layer 32 had substantially the same result as the upper layer 32 of Example 1.

The refractive index n and the extinction coefficient k for light having a wavelength of 193 nm in the lower layer 31 of the mask blank of Example 3 are measured by a spectroscopic ellipsometer (M-2000D manufactured by JA Woollam).
) Was measured. As a result, the refractive index n _L of the lower layer 31 at a wavelength of 193 nm is 1.9.
3. The extinction coefficient k _L was 1.50. The upper layer 32 had substantially the same result as the upper layer of Example 1. Further, the refractive index n _U at the wavelength of 193 nm of the upper layer 32 is changed to the wavelength 19 of the lower layer 31.
The ratio n _U / n _L divided by the refractive index n _L at 3 nm was 0.922. This Example 3
For the mask blank of, a spectrophotometer (Cary 4000 manufactured by Agilent Technologies)
), And the wavelength of the light of the ArF excimer laser having a laminated structure of the phase shift film 2 and the light shielding film 3 (
When the optical density at (about 193 nm) was measured, it was 4.06. In addition, the light-shielding film 3
When the surface reflectance on the opposite side of the phase shift film 2 was measured, it was 52%.

[Manufacturing of phase shift mask]
Next, using the mask blank 100 of Example 3, the phase shift mask 200 of Example 3 was manufactured by the same procedure as that of Example 1. Similar to the case of the first embodiment, for the phase shift mask 200 of the third embodiment, a mask inspection device (Teron 6 manufactured by KLA-Tencor) is used.
When the mask inspection was performed with 00Series), no defect was found in the phase shift pattern 2a. From this, it was confirmed that the same as in Example 1.

[Evaluation of pattern transfer performance]
Similar to the case of the first embodiment, the phase shift mask 200 of the third embodiment is applied to the mask stage of the exposure apparatus capable of irradiating the phase shift mask 200 with ArF exposure light in the illumination system optimized by SMO. Was set, and repeated exposure transfer was performed on the resist film on the semiconductor substrate in the arrangement shown in FIG. The resist film on the semiconductor substrate after exposure transfer was subjected to development processing and the like to form a resist pattern. The resist pattern is SEM
It was confirmed that the resist pattern was formed with high CD accuracy. Image S of the region where the light-shielding band shown in FIG. 3 was exposed and transferred four times, which was a concern for deterioration of CD accuracy.
It was confirmed that the fine patterns p _1d , p _2c , p _3b , and p _4a in the vicinity of ₁₂₃₄ were also formed with high CD accuracy. From this result, it can be said that the circuit pattern can be formed with high accuracy by dry etching using this resist film as a mask.

(Comparative Example 1)
[Manufacturing of mask blank]
The mask blank of Comparative Example 1 was manufactured by the same procedure as that of Example 1 except for the light-shielding film 3. In the light-shielding film of Comparative Example 1, the lower layer is formed of a CrOCN film and the upper layer is formed of a SiO ₂ film. Specifically, a translucent substrate on which a phase shift film is formed is installed in a single-wafer DC sputtering device, and an argon (Ar) and carbon dioxide (CO) are used using a chromium (Cr) target.
₂ ) Reactive sputtering in a mixed gas atmosphere of nitrogen (N ₂ ) and helium (He) (2)
DC sputtering) was performed. As a result, the lower layer of the light-shielding film (CrOCN film) composed of chromium, oxygen and carbon was formed with a film thickness of 43 nm in contact with the phase shift film. Next, a translucent substrate in which the lower layers of the phase shift film and the light-shielding film are laminated is installed in the single-wafer RF sputtering device, and an argon (Ar) gas is sputtered using a silicon dioxide (SiO ₂ ) target. Then, an upper layer of the light-shielding film made of silicon and oxygen was formed with a thickness of 12 nm on the lower layer of the light-shielding film by RF sputtering.

Similar to Example 1, a mask blank in which a phase shift film and a light-shielding film were laminated on the main surface of another translucent substrate under the same conditions was manufactured. The lower and upper layers of the mask blank in Comparative Example 1 were analyzed by X-ray photoelectron spectroscopy (with XPS and RBS correction). As a result, the composition of the lower layer is Cr: 55 atomic%, O: 22 atomic%, C: 12 atomic%, N: 11 atomic%.
The composition of the upper layer was Si: 35 atomic% and O: 65 atomic%. Further, it was confirmed that the difference between the constituent elements in the thickness direction in the inner region of the lower layer and the upper layer was 3 atomic% or less, and there was substantially no composition gradient in the thickness direction in the inner region.

Similar to Example 1, the refractive index n and the extinction coefficient k for light having a wavelength of 193 nm in the lower layer of the mask blank of Comparative Example 1 are measured by a spectroscopic ellipsometer (manufactured by JA Woollam).
It was measured using M-2000D). As a result, the refractive index n of the lower layer at a wavelength of 193 nm
_L was 1.93 and the extinction coefficient k _L was 1.50. The refractive index n _U and the extinction coefficient k U of the upper layer at a wavelength of 193 nm were 1.59, and the extinction coefficient k _U was 0.00. Further, the wavelength 19 of the upper layer 32
The ratio n _U / n _L obtained by dividing the refractive index n _U at 3 nm by the refractive index n _L at the wavelength of 193 nm of the lower layer 31 was 0.824. For the mask blank of Comparative Example 1, a spectrophotometer (
The optical density at the light wavelength (about 193 nm) of the ArF excimer laser having a laminated structure of a phase shift film and a light-shielding film was measured using Agilent Technologies Cary4000) and found to be 3.01. Moreover, when the surface reflectance on the side opposite to the phase shift film of the light-shielding film was measured, it was 11%.

[Manufacturing of phase shift mask]
Next, using the mask blank of Comparative Example 1, the phase shift mask 200 of Comparative Example 1 was manufactured by the same procedure as in Example 1. As in the case of Example 1, the phase shift mask of Comparative Example 1 is subjected to a mask inspection device (Teron600Seri manufactured by KLA-Tencor).
When the mask inspection was performed in es), no defect was found in the phase shift pattern 2a. For this reason, the light-shielding film 3 (thickness is also the same as the conventional one) with the same light-shielding performance as the conventional one (the light-shielding performance is not enhanced by the composition, and the thickness is not increased to secure the optical density. It was confirmed that (.) Sufficiently functions as a hard mask for forming the fine pattern of the resist pattern 4a on the phase shift film.

[Evaluation of pattern transfer performance]
Similar to the case of the first embodiment, the phase shift mask of Comparative Example 1 is applied to the mask stage of the exposure apparatus capable of irradiating the phase shift mask 200 with ArF exposure light in the illumination system optimized by SMO. It was set and repeated exposure transfer was performed on the resist film on the semiconductor substrate in the arrangement shown in FIG. For the resist film on the semiconductor substrate after exposure transfer
A resist pattern was formed by performing development processing and the like. When the resist pattern was observed by SEM, the fine patterns _p1d , _p2c , _p3b in the vicinity of the image _S1234 of the region where the light-shielding band shown in FIG. 3 was exposed and transferred four times, which was concerned about the deterioration of the CD accuracy, were observed. , _P4a was found to have particularly low CD accuracy. From this result, it can be said that when a circuit pattern is formed by dry etching using this resist film as a mask, a circuit defect or the like may occur.

1 Translucent substrate 2 Phase shift film 2a Phase shift pattern 3 Light-shielding film 31 Lower layer 32 Upper layer 3b Light-shielding pattern 31a, 31b Lower layer patterns 32a, 32b Upper layer patterns 4a, 5b Resist pattern 100 Mask blank 200 Phase shift mask

Claims (9)

A mask blank having a structure in which a first film and a second film are laminated in this order from the substrate side on the substrate .
The first film is made of a material having a total content of chromium, oxygen, nitrogen and carbon of 90 atomic% or more.
The first film has a chromium content of 50 atomic% or more, and has a chromium content of 50 atomic% or more .
The second film is made of a material containing metal and silicon, and the total content of metal and silicon is 80 atomic% or more.
A mask blank characterized in that the extinction coefficient k _U of the second film with respect to light having a wavelength of 193 nm is larger than the extinction coefficient k _L of the first film with respect to light having a wavelength of 193 nm. The mask blank according to claim 1, wherein the extinction coefficient k _L of the first film is 2.0 or less, and the extinction coefficient k _U of the second film is larger than 2.0. The refractive index n _U of the second film with respect to light having a wavelength of 193 nm is smaller than the refractive index n _L of the first film with respect to light having a wavelength of 193 nm, and the refractive index n of the second film with respect to light having a wavelength of 193 nm is n. The mask blank according to claim 1 or 2, wherein the ratio n _U / n _L obtained by dividing _U by the refractive index n _L with respect to light having a wavelength of 193 nm of the first film is 0.8 or more. The mask blank according to claim 3, wherein the refractive index n _L of the first film is 2.0 or less, and the refractive index n _U of the second film is smaller than 2.0. The mask blank according to any one of claims 1 to 4, wherein the first film is made of a material having a total content of chromium, oxygen and carbon of 90 atomic% or more. The second film is characterized in that the ratio of the metal content [atomic%] divided by the total metal and silicon content [atomic%] is 5% or more . The mask blank described in either. The mask blank according to any one of claims 1 to 6, wherein the second film is made of a material having a total content of tantalum and silicon of 80 atomic% or more. A method for manufacturing a transfer mask using the mask blank according to any one of claims 1 to 7.
A step of forming a transfer pattern on the second film by dry etching using a fluorine-based gas using a resist film on which a transfer pattern is formed as a mask, and a step of forming the transfer pattern on the second film.
A step of forming a transfer pattern on the first film by dry etching using a mixed gas of chlorine-based gas and oxygen gas with the second film on which the transfer pattern is formed as a mask.
A method for producing a transfer mask, which comprises . A method for manufacturing a semiconductor device, which comprises a step of exposing and transferring a transfer pattern to a resist film on a semiconductor substrate by using the transfer mask manufactured by the method for manufacturing the transfer mask according to claim 8 .

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